NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PROBLEM TO BE SOLVED: To eliminate the need of the write operation before erasing to reduce the time taken for one-shot erase operation and the time taken for the rewrite operation of data in a flash memory comprising a plurality of stack gate type memory cells. SOLUTION: For erasing, a plurality of memory cells inject electrons from their sources 1003 at once into their floating gates 1005, this raising the threshold voltage of the plurality of memory cells. For programming, selected memory cells discharge electrons from their floating gates 1005 at once into their drains 1002, this dropping the threshold voltage of the selected memory cells.